Parol Evidence Rule

Plain English

The parol evidence rule says that once you have a final written contract, you generally can't use outside evidence—like earlier conversations, emails, or handwritten notes—to add to, subtract from, or change what the writing says. The written document is the official record of the deal. There are some exceptions, like if the writing is ambiguous or if fraud is involved, but the basic idea is that the writing controls. This rule protects people from false claims about secret side agreements.

Example

You sign a written lease saying rent is $1,500 per month. Later, you claim the landlord verbally promised to reduce it to $1,200. The parol evidence rule prevents you from using that oral promise to change the written contract unless the writing is unclear or fraud occurred.

Used in a sentence

“The parol evidence rule barred the witness from testifying about the alleged oral modification because the written contract was clear and complete.”

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